This invention relates to an improved negative-resistance semiconductorr device comprising complementary field-effect transistors (hereinafter referred to as FETs), and particularly concerns a unitary negative-resistance circuit device with controllable characteristic of its negative resistance.
Conventional negative-resistance semiconductor devices are known, in one of which a single-element type is realized by a physical mechanism, and in another of which a composite type is composed of a plural number of discrete semiconductor elements wired together to form a circuit. The former type is best represented by that showing N-figured negative-resistance characteristic such as tunnel diodes, Gunn diodes, etc. and that showing S-figured negative-resistance characteristic such as thyristers, uni-junction transistors, etc. The latter type is best represented by a flip-flop circiut showing S-figured characteristic or circuit composed of a serially connected pair of complementary field-effect transistors showing N-figured characteristic.
Out of the abovementioned known devices, that showing the S-figured characteristic is in wide practial use now, but that showing the N-figured characteristic is used only for special uses. The main reason therefor is that in the conventional N-figured negative-resistance single-element realized by the physical mechanism of the tunnel diode, Gunn diode, etc. of the former type, the electrical characteristics are so specified that very limited applications only could be available.
The aforementioned N-figured negative resistance device composed of serially connected complementary field-effect transistors is proposed by IEEE Transaction on circiut theory, March 1963, page 25-35 and by proceedings of IEEE, April 1965, page 404. The proposed device comprises a pair of field-effect transistors of p-channel type and n-channel type, respectively, both to be electrically actuated in depletion mode and connected source-to-source to each other, wherein the gate electrode of each FET is connected to the drain electrode of the other FET. In such device, the characteristic, i.e., first, second and third threshold values are determined by component FETs, and therefore, are fixed. However, there is a need of providing negative resistance devices of various characteristics.